Okay, I was just thinking this today, and I'm wondering if anyone would like to expand on this.
Did anyone ever notice that in the second episode of ID: First Stage -- Keisuke says in disbelief something to the effect of "My FD lost to a 10 year old 86." I think that the chassis AE86 for the Trueno, Levin and Corolla lasted until 1987 at the latest. That places Initial D first stage in roughly 1996-1997 time period. Through 4th stage, only one year has gone by. So why is God Arm driving an S2000? According to the time period, that car shouldn't have come out yet.
Not to start knockin' Initial D, cuz any movie, or television show, be it great or crap always has some discontinuity in it, and this doesn't change the fact that I still think that ID is a great show.